3.无重复字符的最长子串

class Solution {
    public int lengthOfLongestSubstring(String s) {
        if(s.length() == 0)
            return 0;
        
        int max = 1;
        
        for(int i = 0; i < s.length()-1;i++){
            String sub = s.substring(i,i+1);
            int j = i+1;
            for(; j < s.length(); j++){
                if(sub.contains(String.valueOf(s.charAt(j)))){
                    if(sub.length() > max){
                        max = sub.length();
                        break;
                    }
                    else{
                        break;
                    }
                }
                
                 else{
                     sub += String.valueOf(s.charAt(j));
                 }
            }
            if(j == s.length())
                return max > sub.length() ? max : sub.length();
        }
        return max ;
    }
}